1. Field of the Invention
The present invention relates to an information processing apparatus which is connected to a network via a network interface and communicable with an external apparatus.
2. Description of the Related Art
Conventionally, an information processing system which has a power saving mode for minimizing power consumption on standby has been known. As an example of such an information processing system, there is a communication system including an information processing apparatus on the main body side provided with a main central processing unit (CPU) and a network interface card (NIC) apparatus provided with a sub CPU. In general, such a communication system brings the information processing apparatus on the main body side into a power saving mode during the power saving mode and each module of the NIC apparatus which uses less power stands by while being supplied with a normal electric power.
Japanese Patent Application Laid-Open No. 2006-259906 discusses that, when a normal power mode is transferred to a power saving mode to stop supplying the main CPU with electric power, the main CPU notifies the sub CPU of an address of a multicast packet to be responded. This allows the sub CPU to respond instead of the main CPU when the sub CPU receives a multicast packet when the supply of the electric power to the main CPU stopped, which eliminates need for starting the main CPU. In other words, a stoppage in supplying the electric power to the main CPU can be continued longer to increase an effect of power saving.
In recent years, as a technique for encrypting a network path in order to protect confidential information, an encryption system such as Internet protocol security (IPSec) and secure socket layer (SSL) has been known. The use of these techniques can transfer data via a network with data encrypted and prevent leakage of information.
As a standard for authentication used in the connection of a system to a local area network (LAN), an 802.1X is known. The 802.1X limits connection by authentication to prevent a terminal device other than a predetermined terminal device from connecting a system to a computer network.
As described above, information about a packet to be responded when the information processing apparatus on the main body side is brought into a power saving mode is registered into the NIC apparatus to allow the NIC apparatus to respond to a received packet instead of the information processing apparatus on the main body side.
When the NIC apparatus responds instead of the information processing apparatus on the main body side, if a packet transmitted via the network is encrypted, the NIC apparatus may not be able to adequately respond.
In other words, when the NIC apparatus is caused to respond instead of the information processing apparatus on the main body side, a pattern of the packet to be responded by the NIC apparatus and a packet to be transmitted as a response to the packet matching with the pattern are registered into the NIC apparatus. This means that the NIC apparatus which receives the packet matching with the registered pattern transmits the packet corresponding to the pattern. If the packet received by the NIC apparatus is encrypted and then the encrypted packet is compared with the registered pattern, it is determined that the content does not match with the registered pattern even if the content of the packet matches with the registered pattern.
In this case, the information processing apparatus on the main body side is returned from the power saving mode to the normal power mode and the packet received by the NIC apparatus is to be transferred to the information processing apparatus on the main body side. Thus, this increases the number of times that the information processing apparatus on the main body side is returned from the power saving mode to the normal power mode and the effect of saving power is lessened.
The NIC apparatus may include a configuration for encryption and decryption processing similar to the information processing apparatus on the main body side, which, however, may cause the following situation.
When the information processing apparatus on the main body side executes an encrypted communication, the information processing apparatus on the main body side previously performs negotiation with an external apparatus which is the other party for the encrypted communication to acquire and store information to execute the encrypted communication. The stored information is used when the information processing apparatus on the main body side executes the encrypted communication.
However, if the information processing apparatus on the main body side is switched to the power saving mode and the NIC apparatus executes the encrypted communication with an external apparatus, the NIC apparatus is to perform again the negotiation with the external apparatus. Such processing may cause a situation in that both the NIC and the external apparatus are subjected to an unnecessary load and a time-consuming negotiation decreases communication efficiency.
Further, a generally NIC apparatus is poorer in hardware configuration (processing efficiency of CPU and memory capacity) than the information processing apparatus on the main body side. Therefore, it may be difficult for the NIC apparatus to be equipped with a configuration for performing the negotiation with the external apparatus as well as a configuration for performing the encryption and the decryption processing.
This applies to an authentication system such as 802.1X. If the information processing apparatus on the main body side is switched to the power saving mode and the NIC apparatus communicates with the external apparatus instead of the information processing apparatus on the main body side, the negotiation is again to be performed between the NIC apparatus and the external apparatus.